The present invention is directed to film accumulators and more particularly to film accumulators used in conjunction with photo interpretation microscopes; commonly referred to as a stereomicroscope.
Photo interpretation microscopes are usually mounted on a device referred to as a light table such devices provide illumination to assist in viewing details recorded on photographic film and to assist in supporting the photographic film during photo interpretation and/or analysis. Such light table are well known, conventionally support the photo interpretation microscope and provide various devices acting as supports for rolls of film prior to being viewed as well as take up devices to store the film after viewing.
A number of well known procedures are used for obtaining aerial photographs used for photo interpretation. One common procedure provides for a single camera taking a plurality of exposures. Such cameras are commonly mounted on moving vehicles such as airplanes and produce a panoramic view of the ground across the direction of movement. Frequently, a single picture, or frame, will be more than two feet long. Thus the spacing between comparable positions on sequential pictures is usually beyond the limits of extension of the rhomboid arms of photo comparison microscopes and some form of film accumulation is required between the rhomboid arms to permit simultaneous viewing.
A prior art film accumulator was positioned below the light table and was accessed through a slot in the table. This type of accumulator provided either a long take-up or a short take-up of film by choosing one of several predetermined paths through non-adjustable rollers positioned below the light table. Thus the film proceeded from the feed reel; across the top of the table; down through a slot in the table; around one or more rollers and then back up through the slot to the top of the table and continued across the table to the take-up reel. Devices of this type have several disadvantages. One obvious disadvantage is the inconvenience of having to thread the film around the various rollers below the table. Also, a further disadvantage of this prior art accumulator resides in having a slot traversing the light table when the film accumulation feature is not needed. Still another disadvantage of this prior art form of film accumulation results from the requirement to move the microscope instead of the table surface for mensuration. A further disadvantage results in less mensuration accuracy because of the distance which is necessary between the measuring system and the film being measured.
U.S. Pat. No. 3,879,107 is illustrative of a stereo microscope used for image analysis and U.S. Pat. Nos. 4,455,592 and 4,455,593 are illustrative of light table used in combination with photo interpretation microscopes.
U.S. Pat. No. 4,420,121 issued Dec. 13, 1983 illustrates a film accumulation device using a zig-zag pattern across the table surface. Variations in the amount of film to be accumulated are accomplished by varying the position of at least one of the roller assemblies providing the zig-zag pattern.